Image mask film scheme and method

ABSTRACT

A system and method for repairing a photolithographic mask is provided. An embodiment comprises forming a shielding layer over an absorbance layer on a substrate. Once the shielding layer is in place, the absorbance layer may be repaired using, e.g., an e-beam process to initiate a reaction to repair a defect in the absorbance layer, with the shielding layer being used to shield the remainder of the absorbance layer from undesirable etching during the repair process.

This application is a continuation of U.S. patent application Ser. No.14/841,141, filed Aug. 31, 2015, and entitled “Image Mask Film Schemeand Method,” which application is a divisional of U.S. patentapplication Ser. No. 13/649,850, filed Oct. 11, 2012, and entitled“Image Mask Film Scheme and Method,” now U.S. Pat. No. 9,122,175 issuedSep. 1, 2015, which applications are incorporated herein by reference.

BACKGROUND

Generally, photolithographic masks are utilized to pattern an energysource such as light as the light passes through the photolithographicmask from one side to another. The patterned light may then be directedtowards a photoresist material that has been previously applied to, forexample, a semiconductor substrate that is being processed. Thepatterned light will cause a reaction with photoacid generators locatedwithin the photoresist material to form an acid within those areasilluminated by the patterned light. This acid will then react with othercomponents of the photoresist material within the portion illuminated bythe energy source to form a chemically distinct polymer. This chemicallydistinct polymer may then be separated from the unilluminated portion ofthe photoresist to form either a positive or negative image of thepatterned light (depending upon which portion is being removed), in aprocess known as developing the photoresist. Once the photoresist hasbeen developed, the photoresist may be utilized as a mask during theformation of devices, isolation regions, metallization layers, or otherstructures on the semiconductor wafer.

The photolithographic masks may themselves be formed utilizinglithographic techniques, whereby a portion of the photolithographic maskis removed to form the desired pattern. This removal process may involvea chemical etchant that reacts with a portion of the photolithographicmask to chemically modify and remove the desired portions of thephotolithographic mask.

However, during the patterning of the photolithographic mask, defectscan occur that undesirably alter the desired pattern of thephotolithographic mask. These defects may occur by blocking too muchlight, otherwise known as an opaque defect, or by blocking too littlelight, otherwise known as a clear defect. Unless these defects arefixed, the photolithographic mask will transfer the defective pattern tothe semiconductor device, forming defects within the semiconductordevice. Such defects may render the semiconductor device inefficient oreven unusable.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present embodiments, and theadvantages thereof, reference is now made to the following descriptionstaken in conjunction with the accompanying drawings, in which:

FIG. 1 illustrates a photolithographic mask with a substrate, anabsorbance layer, an anti-reflective coating layer, and a shieldinglayer in accordance with an embodiment;

FIG. 2 illustrates a hard mask layer formed over the shielding layer inaccordance with an embodiment;

FIG. 3 illustrates a patterning of the photolithographic mask using thehard mask layer and a defect in accordance with an embodiment;

FIG. 4 illustrates a removal of the hard mask layer from the shieldinglayer in accordance with an embodiment;

FIG. 5 illustrates a repair process used to repair the photolithographicmask in accordance with an embodiment;

FIGS. 6A-6D illustrate a reduction in the rate of reaction with theshielding layer in accordance with an embodiment;

FIG. 7 illustrates a repaired photolithographic mask with the defectremoved in accordance with an embodiment;

FIGS. 8A-8B illustrate a reduction in the amount of defects caused bythe repair process in accordance with an embodiment; and

FIG. 9 illustrates a double layer embodiment of the photolithographicmask in accordance with an embodiment.

Corresponding numerals and symbols in the different figures generallyrefer to corresponding parts unless otherwise indicated. The figures aredrawn to clearly illustrate the relevant aspects of the embodiments andare not necessarily drawn to scale.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

The making and using of the present embodiments are discussed in detailbelow. It should be appreciated, however, that the present disclosureprovides many applicable inventive concepts that can be embodied in awide variety of specific contexts. The specific embodiments discussedare merely illustrative of specific ways to make and use the disclosedsubject matter, and do not limit the scope of the different embodiments.

Embodiments will be described with respect to a specific context, namelya photolithographic mask for use as a reticle in photolithographicprocessing of the 20 nm or less processing nodes. Other embodiments mayalso be applied, however, to other repair processes and masks.

With reference now to FIG. 1, there is shown a photolithographic mask100 with a substrate 101, an absorbance layer 103, an anti-reflectivecoating (ARC) layer 105, and a shielding layer 107. In an embodiment thesubstrate 101 may comprise a translucent material such as quartz thatmay be used to provide support to the remaining structure of thephotolithographic mask 100 while also allowing light to pass throughunimpeded. As such, the substrate 101 is not limited to quartz, and maybe any suitable material that allows radiation to pass through thematerial, such as glass, sapphire, synthetic quartz, fused silica,magnesium fluoride (MgF₂), calcium fluoride (CaF₂), combinations ofthese, or the like. The substrate 101 may have a thickness of betweenabout 6.0 mm and about 6.5 mm, such as about 6.35 mm.

The absorbance layer 103 may be formed on the substrate 101 and may beused to absorb or block radiation such as light from passing through theabsorbance layer 103. As such, the absorbance layer 103 is the layerthat will actually pattern light (e.g., light with a wavelength of 193nm or other light useful for photolithographic purposes) as the lightpasses through the absorbance layer 103. The absorbance layer 103 may beformed using a process such as sputtering, although any other suitableprocess, such as chemical vapor deposition (CVD), plasma deposition,plating, combinations of these, or the like, may alternatively beutilized.

In an embodiment the absorbance layer 103 may be an opaque material,such as an Opaque Molybdenum silicide On Glass (OMOG) layer. In anembodiment the OMOG layer may comprise MoSiOxNy with a molybdenumconcentration of about 8.1% (atomic), a silicon concentration of about41.3% (atomic), and a nitrogen concentration of about 50.6% (atomic). Inan embodiment the absorbance layer 103 may have a thickness of betweenabout 35 nm and about 60 nm, such as about 37 nm, may have a dielectriccoefficient (K) value of between about 2.1 and about 2.8, such as about2.63, and may have an index of reflection (N) value of between about 1.5and about 2.0, such as about 1.82.

However, as one of ordinary skill in the art will recognize, while theabsorbance layer 103 is described as a layer for the absorbance oflight, the processes and embodiments described herein are not limited toonly being utilized with opaque materials. Rather, the processes andembodiments disclosed herein are fully intended to be utilized with awide variety of materials, including transparent materials such astransparent OMOG. These are fully intended to be included within thescope of the embodiments.

The ARC layer 105 is used to reduce or prevent reflection off of thematerials that may affect occur during illumination so that suchreflection does not hinder the desired process. In an embodiment the ARClayer 105 may be one or more layers of an anti-reflective material andmay be the same material as the absorbance layer 103 (e.g., OMOG) with,e.g., a different composition such as a molybdenum composition of 1˜2%,a silicon composition of 50˜55%, and a nitrogen composition of 40˜50%.However, other anti-reflective materials such as chromium oxide (CrO),calcium fluoride, magnesium fluoride, metal nitroso compounds, metalhalide, ITO, silicon oxide (SiO₂), tantalum oxide (TaO₅), aluminum oxide(A1 ₂O₃), titanium nitride (TiN), zirconium oxide (ZrO), aluminum (Al),silver (Ag), gold (Au), indium (In), combinations thereof, or the like,may alternatively be utilized. The ARC layer 105 may be formed using ansputter deposition process, a plasma sputter deposition process, or thelike, and may be formed to a thickness of between about 5 and about 20nm, such as about 18 nm, have a K value of between about 0.7 and about0.9, such as about 0.82, and an N value of between about 2.1 and about2.5, such as about 2.33.

Over the ARC layer 105, the shielding layer 107 may be formed in orderto modify the etch rate of the materials of the photolithographic mask100 during a defect repair process (not illustrated in FIG. 1 butillustrated and discussed below with respect to FIG. 5) and bettercontrol the repair process. In an embodiment the shielding layer 107 maybe formed to have a thickness of between about 5 nm and about 20 nm,such as about 10 nm, and may comprise one or more layers of material.

In an embodiment the shielding layer 107 may comprise a material similarto the absorbance layer 103. In an embodiment in which the absorbancelayer 103 is an OMOG layer comprising MoSiOxNy, the shielding layer 107may similarly comprise MoSiOxNy, but will have a different concentrationof the atoms in order to increase the activation energy of the shieldinglayer 107 over the absorbance layer 103. For example, in one embodimentthe shielding layer 107 may have a molybdenum composition of betweenabout 1% to about 5% and comprise a silicon rich MoSiOxNy, with asilicon concentration greater than that of the absorbance layer 103,such as being greater than about 41.3%, such as between about 45% andabout 52%. In some embodiments, the shielding layer 107 may have asilicon composition of about 46.3% (with a molybdenum concentration of3.8% and a nitrogen concentration of about 49.9%) or even 51.9% (with amolybdenum concentration of 1.6% and a nitrogen concentration of about46.5%). In a silicon-rich embodiment the shielding layer 107 may have aK value of between about 0.5 and about 0.7, such as about 0.69, and an Nvalue of between about 2.1 and about 2.5, such as about 2.34. In such anembodiment the photolithographic mask 100 may have a reflectance percentof about 14.8%.

By forming the shielding layer 107 to be silicon rich, the shieldinglayer 107 has a higher binding energy and a higher activation energythan the absorbance layer 103. For example, when the shielding layer 107is silicon rich, there is an abundance of silicon oxide material (e.g.,silicon atoms bonded to oxygen atoms) within the shielding layer 107,which material has a binding energy of 3231 KJ/Mol. This is much higherthan the binding energy of 1350 KJ/Mol that the MoSi-rich materials ofthe absorbance layer 103. This larger binding energy and activationenergy is utilized along with a higher enthalpy of vaporization and asmaller free volume in order to lower the reaction rate of the shieldinglayer 107 during an etching process (described further below withrespect to FIG. 5) used to repair the photolithographic mask 100. Byslowing the rate of reaction, the reaction can be better controlled andundesired removal of material from the photolithographic mask 100 may bereduced or avoided, leading to a better repair process. Additionally, byforming the shielding layer 107 to be silicon rich, the shielding layer107 will also be harder than the absorbance layer 103, leading to betterprotection to the absorbance layer 103.

Additionally, in an embodiment in which the shielding layer 107 is thesame material as the absorbance layer 103, the same process flows may beutilized to form the shielding layer 107 and the absorbance layer 103,allowing such embodiments to be fully integrated into process flowswithout additional retooling. For example, the absorbance layer 103, theARC layer 105 and the shielding layer 107 may be formed in a singleprocess step by adjusting the parameters during formation, or else maybe formed using separate process steps that are independent from eachother. Further, changing the composition to the shielding layer 107 hasa minimal effect on the reflectivity on the shielding layer 107. Forexample, in an embodiment in which the shielding layer is formed asdescribed above, the shielding layer 107 may have a reflectivity ofabout 14.8%, which is comparable to the absorbance layer 103reflectivity of about 12%.

However, while the embodiment described above is an embodiment in whichthe shielding layer 107 is the same material as the absorbance layer103, the shielding layer 107 is not limited as such. Rather, anymaterial that can be used to slow the rate of reaction of the absorbancelayer 103 during a repair process may alternatively be utilized. Forexample, the shielding layer 107 may be silicon nitride, silicon oxide,silicon oxynitride, or any other suitable nitride or oxide material.Additionally, the shielding layer 107 may also comprise a metal/metaloxide material such as tantalum/tantalum oxide (Ta/TaO) ortitanium/titanium oxide (Ti/TiO). All of these materials and othermaterials which raise the activation energy of the photolithographicmask 100 are fully intended to be included within the scope of theembodiments.

Optionally, the shielding layer 107 may be formed to have a greaterthickness than the ARC layer 105. For example, in an embodiment the ARClayer 105 may have a thickness of about 8 nm while the shielding layer107 may have a thickness larger than about 8 nm, such as about 10 nm.However, any desired thicknesses may alternatively be utilized. In suchan embodiment the reflectance of the photolithographic mask 100 may havea reflectance percent of about 15.2%.

FIG. 2 illustrates a formation of a hard mask layer 201 that will beused for patterning the absorbance layer 103. In an embodiment the hardmask layer 201 may be a layer of chromium formed using, e.g., a sputterdeposition process, although other suitable materials and methods offormation may alternatively be utilized. In an embodiment the hard masklayer 201 may be formed to a thickness of between about 5 nm and about10 nm, such as about 5 nm.

FIG. 3 illustrates a patterning of the hard mask layer 201, theshielding layer 107, the ARC layer 105, and the absorbance layer 103. Inan embodiment the hard mask layer 201 may be initially patterned byplacing a photoresist material (not illustrated) onto the hard masklayer 201 using, e.g., a spin-coating process. Once in place, thephotoresist material is patterned using, e.g., an e-beam tool totransfer the desired pattern from, e.g., a GDS file where the pattern isstored, to the photoresist material. The photoresist material is thenbaked and developed for use as a mask.

Additionally, as one of ordinary skill in the art will recognize, theabove described method of applying a photoresist and transferring thepattern with an e-beam tool is not the only method which may be utilizedto pattern the hard mask layer 201. Rather, any suitable method ofpatterning, including applying the photoresist, exposing the photoresistto a patterned energy source such as light, and developing thephotoresist, may alternatively be utilized. This and any other suitablemethod of patterning the hard mask layer 201 are fully intended to beincluded within the scope of the embodiment.

Once the photoresist has been patterned, the photoresist may be used asa mask to pattern the underlying hard mask layer 201. In an embodimentin which the hard mask layer 201 is chromium, the pattern may betransferred from the photoresist to the hard mask layer 201 using, e.g.,a dry etch process using etchants such as chlorine (Cl₂) and oxygen (O₂)plasma. However, any suitable etchants or processes may alternatively beutilized to transfer the pattern from the photoresist to the hard masklayer 201.

Once the hard mask layer 201 has been patterned, the photoresist may bestripped using, e.g., an ashing process or wet etching process, and thehard mask layer 201 is then used as a mask in order to pattern theunderlying shielding layer 107, the ARC layer 105, and the absorbancelayer 103 in order to form openings 301. In an embodiment in which theshielding layer 107, the ARC layer 105, and the absorbance layer 103 areall the same material (e.g., OMOG), a dry etch process utilizingetchants such as silicon fluoride (SF₆) and oxygen (O₂) plasma may beutilized to transfer the pattern from the hard mask layer 201 to theabsorbance layer 103.

Alternatively, if the shielding layer 107 is a different material thaneither the ARC layer 105 or the absorbance layer 103, one or moreetching processes may be utilized to etch the absorbance layer 103 andtransfer the pattern. Any suitable process or series of processes may beutilized in order to transfer the pattern from the hard mask layer 201to the absorbance layer 103.

FIG. 3 also illustrates a defect 303 that may occur during thepatterning of the photolithographic mask 100. For example, given thesmall sizes that are found in the photolithographic mask 100, thepatterning of the hard mask layer 201 may undesirably result in the hardmask layer 201 not being fully removed in certain areas. Without thehard mask layer 201 being removed, the underlying layers (such as theshielding layer 107, the ARC layer 105, and the absorbance layer 103),will remain masked and will not be removed during the subsequentetching, even though they are desired to be removed, causing the defect303 to occur. Without this section of the absorbance layer 103 beingremoved, this portion of the photolithographic mask 100 remains opaqueto light transmission, and is known as an opaque defect.

FIG. 4 illustrates a removal of the hard mask layer 201 after thepatterning of the shielding layer 107, the ARC layer 105, and theabsorbance layer 103. In an embodiment the hard mask layer 201 may beremoved using a stripping process such as a wet etch to strip the hardmask layer 201 from the shielding layer 107. However, as can be seen,the defect 303 remains within the shielding layer 107, the ARC layer105, and the absorbance layer 103 after the hard mask layer 201 has beenremoved.

This defect may be found by verifying the photolithographic mask 100. Inparticular, the defect may be found by performing a luminosity test onthe photolithographic mask 100, which may illustrate where the defect303 has occurred. This verification process may be performed using aZess MG45 or HR32 e-beam repair tool.

FIG. 5 illustrates the start of a repair process that may be used torepair the defect 303 in the shielding layer 107, the ARC layer 105, andthe absorbance layer 103. In an embodiment the repair process may beginby placing the photolithographic mask 100 into a reaction chamber 501with an influent 503 and an effluent 505. The reaction chamber 501 alsocontains an electron beam system 507 which will be used to deliver anelectron beam 509 where desired in order to initiate and promotechemical etching at the surface of the photolithographic mask 100(described in more detailed below).

Once the photolithographic mask 100 has been placed into the reactionchamber 500, the reaction chamber 500 is hermetically sealed away fromthe ambient environment and the reaction chamber 500 is purged prior tothe introduction of etchants 511 that will be used to repair thephotolithographic mask 100. As one of ordinary skill in the art willrecognize, the etchants 511 that will be utilized to repair thephotolithographic mask 100 are dependent at least in part on the precisematerials utilized for the absorbance layer 103, the ARC layer 105, andthe shielding layer 107. However, in an embodiment in which theabsorbance layer 103, the ARC layer 105, and the shielding layer 107 area material such as OMOG, the etchant 511 may be xenon difluoride (XeF₂).However, any suitable etchant or combination of etchants, such as acombination of SF₆ and O₂, may alternatively be utilized to help repairthe photolithographic mask 100.

Once the etchant 511 has been selected and the reaction chamber 501 hasbeen sealed and purged, the reaction chamber 501 may be brought to thedesired reaction conditions. In an embodiment the pressure in thereaction chamber 501 may be brought and held to a pressure of betweenabout 2e⁻⁵ mbar and about 5e⁻⁵ mbar, such as about 3.7e⁻⁵ mbar.Additionally, the temperature of the reaction chamber 501 (and thephotolithographic mask 100 within the reaction chamber 501), may bebrought to and held between about 20° C. and about 24° C., such as aboutless than 21° C. and a gas temperature is about −10° C. Such processconditions allow for better control of the rates of reaction that willoccur within the reaction chamber 501 between the photolithographic mask100 and the etchants 511.

Once the reaction chamber 501 has been brought to the desiredconditions, the etchant 511 may be introduced into the reaction chamber501 through the influent 503. In an embodiment the etchant 511 may beintroduced into the reaction chamber 501 at a flow rate of between about0.05 sccm and about 0.5 sccm, such as about 0.1 sccm, while the etchants511 may be removed from the reaction chamber 501 through the effluent505 so that the dwell time is between about 0.04 s and about 0.1 s, suchas about 0.08 s. During the process, the etchant 511 may be continuallysupplied to the reaction chamber 501 through the influent 503 andcontinually removed from the reaction chamber 501 through the effluent505. Once introduced, the etchant 511 will fill the reaction chamber501, with a portion of the etchant 511 being located adjacent to thesurface of the shielding layer 107 (the remainder of the etchant 511within the reaction chamber 501 is not illustrated in FIG. 5 forclarity).

Optionally, the etchant 511 may be diluted using a suitable diluent.Diluting the etchant 511 with a diluent reduces the concentration of theetchant 511 in the reaction chamber 501, thereby also helping to lowerthe rate of reaction between the shielding layer 107 and the etchant511. This lowering of the rate of reaction allows for a better processcontrol of the reaction, which allows for less defects to occur duringthe repair process. In an embodiment water (H₂O) may be utilized as adiluent, although other gases, such as nitrous oxide (NO₂), mayalternatively be utilized. The diluent may be added at a flow rate ofbetween about 1 sccm and about 3 sccm, such as about 1.5 sccm.

Once the etchant 511 has been introduced into the reaction chamber 501and the process conditions within the reaction chamber 501 have come toprocessing conditions, the electron beam system 507 may be started togenerate the electron beam 509 to initiate a chemical reaction betweenthe XeF₂ and the material on the photolithographic mask 100. In anembodiment the electron beam system 507 may use one or more sources ofelectrons, such as a field electron emission source or thermionic sourceusing, e.g., heated tungsten/zirconium oxide in order to generateelectrons. Once generated, the electrons may be passed through one ormore lenses (not individually illustrated in FIG. 5) in order to focusand direct the electrons towards the photolithographic mask 100 as theelectron beam 509. The one or more lenses may be, e.g., magnetic lenses,although any suitable lens may alternatively be utilized. For example,in some embodiment, an electrostatic lens may be suitable, and mayalternatively be used.

In an embodiment the electron beam 509 is directed towards the defect303 on the photolithographic mask 100. As the electron beam 509intersects the etchant 511 and the shielding layer 107, the electronbeam 509 initiates a reaction between the etchant 511 and the materialof the shielding layer 107 in order to begin etching and removing theshielding layer 107, the ARC layer 105, and the absorbance layer 103 toremove the defect 303. By initiating and maintaining the etching alongthe presence of the electron beam 509, the defect 303 may be etched awayand removed in order to repair the photolithographic mask 100.

However, during the repair process utilizing the electron beam 509, theetching is not perfectly defined by the presence of the electron beam509, and undesirable etching may occur in places other than the defect303. In particular, without the presence of the shielding layer 107, theetchant 511 (e.g., XeF₂) could also undesirably etch other portions ofthe absorbance layer 103, causing an undesirable fall in the blockingability of the absorbance layer 103, creating another defect (e.g., aclear defect) during the repair process. Such a fall would allow lightto pass through those areas of the absorbance layer 103 during use ofthe photolithographic mask 100.

In particular, without the shielding layer 107, the reaction ratebetween the etchant 511 and the absorbance layer 103 appears to beactivation controlled rather than controlled by the mass transfer of thereactants and the products. For example, when an mixture of etchantssuch as SF₆ and O₂ is utilized, the absorbance layer 103 (e.g., the OMOGlayer) will react with the etchants at the rate illustrated by Equation1:r _(A)=0.6784 W _(ICP) exp(−79.55/V _(DCB))C ^(1/5) _(SF6) C ^(1/2)_(O2)   Eq. 1

-   -   Where: W_(ICP) is a plasma source power        -   V_(DCB) is a DC bias voltage        -   C_(SF6) is a concentration of SF₆        -   C_(O2) is a concentration of O₂            As can be seen, the gaseous reactant has a low reaction            order and has a weak effect on the reaction rate. As such,            the gas-solid reaction is activation controlled rather than            mass-transfer controlled.

By utilizing the occurrence that the reaction is activation controlled,the presence of the shielding layer 107 may be used to increase theactivation energy at the gas-solid interface between the etchant 511 andthe shielding layer 107, thereby working to lower the reaction rate andprovide a shielding or masking function to the underlying layers (e.g.,the ARC layer 105 and the absorbance layer 103). This remains true evenif a similar material (e.g. OMOG) is utilized for both the absorbancelayer 103 and the shielding layer 107, as long as the composition of thematerial used for the shielding layer 107 has a higher activation energythan the composition of the material used for the absorbance layer 103.By forming the shielding layer 107 to have a higher activation energy,the higher activation energy, along with the material's enthalpy ofvaporization, will lower the reaction rate at the gas-solid interface,thereby leading to a better controlled reaction and less defectsoccurring during the repair process.

In addition to controlling the reaction rate of the etching reaction,the use of a similar material as the absorbance layer 103 but with adifferent composition also has two additional benefits. In particular,the shielding layer 107 may be formed to a composition that has asmaller free volume and is harder than the absorbance layer 103. Thesefunctions may work together to help protect the underlying layers suchas the ARC layer 105 and the absorbance layer 103.

The rate of reaction using an etchant such as SF₆ or CF₄ between theshielding layer 107, the ARC layer 105, and the absorbance layer 103 isillustrated in FIGS. 6A-6B. As illustrated in FIG. 6A, the ARC layer 105(labeled as Section I in FIG. 6A with a molybdenum composition of 1˜2%and a silicon composition of 50˜55%) is about 18 nm thick and is etchedin about 3 seconds, leading to an etch rate of about 60 Å/sec.Additionally, the absorbance layer 103 in FIG. 6A is illustrated as fourdifferent regions label Section II (with a molybdenum composition of8.1% and a silicon composition of 41.3%), Section III (with a molybdenumcomposition of 7.0% and a silicon composition of 42%), Section IV (witha molybdenum composition of 6.0% and a silicon composition of 43%), andSection V (with a molybdenum composition of 5.5% and a siliconcomposition of 43.5%), respectively, wherein each section has a slightlydifferent Mo doping. However, as can be seen, with Section II beingabout 18 nm thick and the rest being about 9 nm thick, the etch rate ofthe absorbance layer is between about 10 Å/sec and 18 Å/sec (Section II:10 Å/sec, Section III: 12.8 Å/sec, Section IV: 15 Å/sec, and Section V,18 Å/sec).

However, in FIG. 6B, the etch rate of the shielding layer 107 isillustrated. With a thickness of about 76 nm and a molybdenumcomposition of 3.8% and a silicon composition of 46.3%, the shieldinglayer 107 has an etch rate of about 5 Å/sec. This etch rate is muchlower than the etch rates illustrated above in FIG. 6A, and allows formuch greater process control and masking from the shielding layer 107 asthe shielding layer 107 protects the ARC layer 105 and the absorbancelayer 103 during the etching of the repair process.

FIGS. 6C-6D illustrate this reduction in the rate of reaction in anotherfashion, with FIG. 6C illustrating an etch of an absorbance layer 103with a molybdenum composition of 8.1% and a silicon composition of41.3%. With this composition and a thickness of about 550 Å thick, theabsorbance layer 103 was etched using a loop etch and a cut pointetching signal stop loop of 1650. In this etch the etching process tookapproximately three minutes to etch the 550 A of material.

However, FIG. 6D illustrates an etch of the shielding layer 107 with amolybdenum composition of 1˜5% and a silicon composition of 45˜50%. Withthis composition, the shielding layer 107 material using etched using aloop etch and a cut point etching signal stop loop of 1870 and athickness of about 560 Å. In this etch the etching process tookapproximately four minutes to etch the 560 Å of the shielding layer 107material. As such, using the shielding layer 107 material the reactionrate of the repair process may be slowed down by 30%, allowing for abetter process control and less undesirable damage during the repairprocess.

FIG. 7 illustrates a resulting structure after the defect 303 has beenremoved from the photolithographic mask 100. However, by including theshielding layer 107 to help reduce the activation energy of the reactionand provide a shielding or masking function, undesirable etching of thephotolithographic mask 100 in areas other than the defect 303 arereduced or eliminated. By reducing this undesirable etching, additionaldefects may be avoided, and a more efficient photolithographic mask 100may be obtained.

FIGS. 8A-8B illustrate comparisons between repair defects that can occurwithout the shielding layer (FIG. 8A) and the lack of repair defectsthat occurs with the shielding layer (FIG. 8B). As can be seen in FIG.8A, without the shielding layer 107, additional defects, such as defectsthat register a maximum intensity of greater than 0.6793, can occur inthe photolithographic mask 100 during a repair process, such as thedefect 801 along line 8-8′ illustrated in FIG. 8A. In the chart of FIG.8A, this defect is illustrated by the increase in the intensity profileat line 8-8′, which has an Aims intensity increase of about 17.2%.

FIG. 8B illustrates the reduction in defects that can occur when theshielding layer 107 is utilized to control the activation energy and therate of reaction. In particular, the defects have been greatly reducedfrom the structure in FIG. 8A, with the defects having an intensity ofno greater than about 0.6548, only registering an increase in theintensity profile of about 2.1%, much less than the increase inintensity of 17.2% in FIG. 8A.

FIG. 9 illustrates another embodiment which utilizes a double layerstructure instead of the triple layer structure (e.g., the absorbancelayer 103, the ARC layer 105, and the shielding layer 107) describedabove with respect to FIGS. 1-8. In this embodiment the absorbance layer103 is utilized with the shielding layer 107, but the ARC layer 105 isnot utilized. In such as embodiment the absorbance layer 103 may beformed to a thickness of between about 35 and about 60 nm, such as about37 nm. The shielding layer 107 may be formed to thickness of betweenabout 5 nm and about 20 nm, such as about 18 nm. In this embodiment thephotolithographic mask 100 may have a reflectance percent of about15.8%.

Once the photolithographic mask 100 has been manufactured, inspected,verified, and repaired if necessary as described above, thephotolithographic mask 100 may be utilized to help pattern, e.g.,structures on a semiconductor wafer (not illustrated). For example, thephotolithographic mask 100 may be placed into a photolithographicillumination machine. Once in place, the photolithographic mask 100 maybe illuminated by an energy source, with the absorbance layer 103blocking portions of the light to form a patterned light pattern. Thispatterned light pattern may be focused and directed towards aphotosensitive material on a semiconductor substrate, illuminating thephotosensitive material in a desired pattern. Once illuminated, thephotosensitive material may be developed and used as a mask to formdevices, metallization layers, isolation regions, and other structureson or within the semiconductor wafer.

In accordance with an embodiment, a method for forming aphotolithographic mask comprising forming an absorbance layer over asubstrate and forming a shielding layer over the absorbance layer,wherein the shielding layer has a higher activation energy than theabsorbance layer, is provided. The absorbance layer is repaired usingthe shielding layer as a mask.

In accordance with another embodiment, a method of repairing aphotolithographic mask comprising directing an electron beam at ashielding layer overlying an absorbance layer of a photolithographicmask, wherein both the shielding layer and the absorbance layer comprisemolybdenum and silicon and wherein the shielding layer has a higheractivation energy than the absorbance layer, is provided. A portion ofthe absorbance layer is removed through the shielding layer utilizingthe electron beam.

In accordance with yet another embodiment, a photolithographic maskcomprising a substrate and an absorbance layer over the substrate isprovided. The absorbance layer has an intensity profile less than about0.66.

Although the present embodiments and their advantages have beendescribed in detail, it should be understood that various changes,substitutions and alterations can be made herein without departing fromthe spirit and scope of the disclosure as defined by the appendedclaims. For example, the materials utilized for the shielding layer andthe materials utilized for the absorbance layer may be adjusted asdesired while still remaining within the scope of the embodiments.Additionally, the various methods to form and remove the layers may bemodified as desired.

Moreover, the scope of the present application is not intended to belimited to the particular embodiments of the process, machine,manufacture, composition of matter, means, methods and steps describedin the specification. As one of ordinary skill in the art will readilyappreciate from the disclosure, processes, machines, manufacture,compositions of matter, means, methods, or steps, presently existing orlater to be developed, that perform substantially the same function orachieve substantially the same result as the corresponding embodimentsdescribed herein may be utilized according to the present disclosure.Accordingly, the appended claims are intended to include within theirscope such processes, machines, manufacture, compositions of matter,means, methods, or steps.

What is claimed is:
 1. A method comprising: depositing a structure overa substrate, wherein the structure has a first rate of reaction, thestructure comprising: an absorbance layer over the substrate; and ananti-reflective layer over the absorbance layer; and modifying the firstrate of reaction of the structure to a second rate of reaction of thestructure different from the first rate of reaction; and repairing thestructure after the modifying the first rate of reaction until theabsorbance layer has an intensity profile less than about 0.66.
 2. Themethod of claim 1, wherein the modifying the first rate of reaction ofthe structure to the second rate of reaction of the structure comprisesdepositing a shielding layer.
 3. The method of claim 2, wherein theshielding layer and the absorbance layer comprise a first material withdifferent compositions.
 4. The method of claim 3, wherein theanti-reflective layer comprises the first material with a differentcomposition.
 5. The method of claim 4, wherein the first material isopaque molybdenum silicide.
 6. The method of claim 2, wherein theshielding layer comprises a metal/metal oxide material.
 7. A methodcomprising: depositing a layer of opaque molybdenum silicide onto asubstrate, wherein the layer of opaque molybdenum silicide comprises: afirst region adjacent to the substrate with a first silicon composition;a second region on an opposite side of the first region from thesubstrate, the second region having a second silicon compositiondifferent from the first silicon composition; a third region on anopposite side of the second region from the substrate, the third regionhaving a third silicon composition higher than the first siliconcomposition; patterning the layer of opaque molybdenum silicide; andrepairing the layer of opaque molybdenum silicide.
 8. The method ofclaim 7, wherein the second silicon composition is between 50% and 55%.9. The method of claim 8, wherein the third silicon composition isbetween 45% and 52%.
 10. The method of claim 7, wherein the repairingthe layer of opaque molybdenum silicide is performed at least in partwith an electron beam process.
 11. The method of claim 7, wherein thethird region has a higher activation energy than the first region. 12.The method of claim 7, wherein the first region has a thickness ofbetween 35 nm and 60 nm.
 13. The method of claim 12, wherein the secondregion has a thickness of between 5 nm and 20 nm and wherein the thirdregion has a thickness of between 5 nm and 20 nm.
 14. The method ofclaim 7, wherein the opaque molybdenum silicide comprises nitrogen. 15.A method comprising: using a first set of deposition parameters todeposit a first layer of opaque molybdenum silicide with a firstconcentration of silicon; using a second set of deposition parametersdifferent from the first set of deposition parameters to deposit asecond layer of opaque molybdenum silicide with a second concentrationof silicon higher than the first concentration of silicon; using a thirdset of deposition parameters different from the first set of depositionparameters and different from the second set of deposition parameters todeposit a third layer of opaque molybdenum silicide with a thirdconcentration of silicon higher than the first concentration of silicon;patterning the first layer, the second layer, and the third layer; andrepairing the first layer.
 16. The method of claim 15, wherein therepairing the first layer utilizes at least in part an electron beamprocess.
 17. The method of claim 16, wherein the repairing the firstlayer utilizes an etchant.
 18. The method of claim 17, wherein therepairing the first layer is performed at a pressure of between 2e⁻⁵mbar and 5e⁻⁵ mbar.
 19. The method of claim 18, wherein the repairingthe first layer is performed at a temperature of between 20° C. and 24°C.
 20. The method of claim 19, wherein the etchant is introduced to thefirst layer at a flow rate of between 0.05 sccm and 0.5 sccm.